This application is based on application no. 11-218980 filed in Japan, the contents of which are hereby incorporated by reference.
The present invention relates to a liquid crystal light modulating element.
A liquid crystal light modulating element includes a liquid crystal material having a light modulation function, such that when a voltage is impressed to the liquid crystal material via electrodes, the molecular alignment of the liquid crystal material changes and this change in molecular alignment is used as a shutter.
A liquid crystal light modulating element normally includes two substrates, at least one of which is transparent, together with electrodes, and the liquid crystal material is located in between the two substrates.
In a liquid crystal light modulating element in which a liquid crystal material is located between two substrates, a problem arises that if the gap between the two substrates is not uniform in the light modulation range, display performance is degraded. Therefore, the problem arises of how to maintain a uniform gap between the two substrates.
Conventionally, when such a liquid crystal light modulating element is constructed, the gap between the substrates is controlled by applying a sealing material in which a gap regulating materialxe2x80x94termed spacersxe2x80x94is dispersed onto the substrate in the outer areas surrounding the light modulation range by means of screen printing or another method, thereby dispersing the spacers in the light modulation range as well.
However, as liquid crystal light modulating elements have increased in size and quality, it has become essential to ensure that the gap between the substrates is uniform over their entire area. The conventional method, in which the sealing material within which the spacers are dispersed is applied to the substrate outer areas surrounding the light modulation range, thereby dispersing the spacers inside the light modulation range, entails the problem that variations in the gap distance occur between the center of the substrates and the areas on the periphery of the substrates. This problem is particularly conspicuous in light modulating elements that use ferroelectric liquid crystal and in light modulating elements that use the selective reflection property of cholesteric (chiral nematic) liquid crystal. In other words, in ferroelectric liquid crystal elements, the non-uniformity of the gap between the substrates results in unevenness in the orientation of the liquid crystal molecules, which leads to a degradation of display performance, while in a cholesteric liquid crystal element, where matrix driving is used, for example, the non-uniformity of the gap between the substrates results in a degradation of the threshold characteristic when matrix driving is performed, and an uneven display.
As a means to resolve the problems identified above, Japanese Laid-Open Patent Application Hei 11-109368 discloses a liquid crystal light modulating element that comprises a pair of substrates, at least one of which is transparent, and a liquid crystal light modulating layer that is sandwiched between the two substrates, wherein the liquid crystal light modulating layer comprises a liquid crystal material that performs light modulation, spacers that maintain the gap between the substrates at a prescribed distance, and resin bodies of which a thermoplastic high-polymer material forms the principal component, where the resin bodies are located within the light modulation range in accordance with a prescribed principle and serve as an adhesive to bond and support the two substrates.
In the above-described liquid crystal light modulating element, the resin bodies create a strong bond between the pair of substrates so that the gap between them is maintained at a uniform distance over their entire area. It also increases the productivity when manufacturing the element.
In a liquid crystal light modulating element having the construction described above, where multiple pixels are formed in a matrix arrangement, it is preferable that the principle governing the location of the resin bodies specify that they should be located (1) between each pixel so as to prevent a reduction in the effective display rate of the liquid crystal light modulating element, and (2) at the corners of all of the pixels, i.e., in all areas at which the spaces between the vertical columns and the horizontal rows of the pixels intersect, in order to improve the strength of the liquid crystal light modulating element.
However, in a liquid crystal light modulating element having a construction in which the resin bodies are located at the corners of all pixels, the following problems exist.
FIGS. 11A and 11B show a partial plan view of one example of a conventional liquid crystal light modulating element. FIG. 11A shows pixels (a) and pixel spaces (a1), as well as the principle governing the location of the resin bodies (b) in a low-resolution liquid crystal light modulating element. FIG. 11B shows pixels (axe2x80x2) and pixel spaces (a2) (which are smaller than spaces (a1)), as well as the principle governing the location of the resin bodies (bxe2x80x2), in a high-resolution liquid crystal light modulating element. In FIG. 11B, the pixel space (a2) appears to be essentially the same size as that of the pixel space (a1) in FIG. 11A, with the resin bodies (b) larger than the pixel space (a2). In fact, the pixel space (a2) shown in FIG. 11B is smaller than the pixel space (a1) shown in FIG. 11A, and the pixels (a) and resin bodies (b) shown in FIG. 11A are the same size as the pixels (axe2x80x2) and resin bodies (bxe2x80x2) shown in FIG. 11B, respectively.
In the liquid crystal light modulating elements shown in FIGS. 11A and 11B, the resin bodies are located at all of the corners of the square pixels, such that there are resin bodies between each pixel.
However, in a liquid crystal light modulating element of this construction, to make the element high-resolution and high-detail, the resin bodies must be placed with a commensurate degree of density, which entails a lower production efficiency for the element. Moreover, in a high-resolution liquid crystal light modulating element, the space between each pixel (axe2x80x2) becomes narrow, and the resin bodies (bxe2x80x2) obstruct the display areas and reduce the effective display rate, as shown in FIG. 11B.
The same problems exist in a multi-layered liquid crystal light modulating element in which the liquid crystal light modulating element is obtained by means of multiple adjacent layers.
In view of the above-described shortcomings of the conventional liquid crystal light modulating element, the present invention pertains to a liquid crystal light modulating element that has a pair of substrates and a liquid crystal light modulating layer sandwiched between the substrates and in which multiple pixels are aligned in a matrix arrangement, and a multi-layered liquid crystal light modulating element comprising multiple liquid crystal light modulating elements stacked in a layered fashion, wherein increasing the resolution does not reduce the production efficiency for the elements, and a good effective display rate and strength can be maintained.
In order to resolve the problems identified above, the present invention provides:
(1) a liquid crystal light modulating element that has a pair of substrates and a liquid crystal light modulating layer sandwiched between the substrates and in which multiple pixels are aligned in a matrix arrangement, wherein the liquid crystal light modulating layer has a liquid crystal material that performs light modulation, spacers that control the size of the gap between the pair of substrates, and resin bodies that are located inside the light modulation range and support the pair of substrates, and wherein the resin bodies are systematically located according to the principle that (i) they are located in the areas of intersection between the vertical columns and horizontal rows of space between the pixels, but (ii) no resin body is located in at least one of the corners of each pixel, and
(2) a multi-layered liquid crystal light modulating element comprising multiple liquid crystal light modulating element layers that have a pair of substrates and a liquid crystal light modulating layer sandwiched between the substrates and in which multiple pixels are aligned in a matrix arrangement, wherein the liquid crystal light modulating layers in each liquid crystal light modulating element layer have a liquid crystal material that performs light modulation, spacers that control the size of the gap between the pair of substrates, and resin bodies that are located inside the light modulation range and support the pair of substrates, and wherein the resin bodies are systematically located in each liquid crystal light modulating layer according to the principle that (i) they are located in the areas of intersection between the vertical columns and horizontal rows of space between the pixels, but (ii) no resin body is located in at least one of the corners of each pixel.